Solid Phase Synthesis
Solid phase synthesis is an established and effective method for the preparation of peptides, and offers advantages over conventional solution phase chemistry in terms of purification and simplicity (Atherton E, Sheppard R C, Solid Phase Peptide Synthesis: A Practical Approach; IRL Press at Oxford University Press: Oxford, 1989). Solid phase synthesis may also be used for the preparation of non-peptide molecules (Leznoff C C, Acc. Chem. Res., 1978, 11, 327-333) and recently there has been considerable interest in the application of this methodology to the synthesis of combinatorial libraries for biologically active lead compound optimisation and discovery (Moos W H et al., Annu. Rep. Med. Chem., 1993, 28, 315-324).
Solid phase synthesis requires an appropriate solid substrate which carries a plurality of functional groups to which the first reactive entity in the proposed synthesis may be covalently coupled, and from which the desired molecule may be cleaved after assembly. The solid substrate should be compatible with the solvents and reaction conditions that are to be used in the peptide or non-peptide synthesis.
The final step in solid phase synthesis is the cleavage of the covalent bond between the desired peptide or non-peptide molecule and the linker. It is desirable that the conditions for the cleavage are orthogonal to those used during the reactions employed for the synthesis of the peptide or non-peptide on the solid support such that inadvertent cleavage does not occur during the synthesis. Furthermore, the conditions for cleavage should be relatively mild such that they do not result in degradation of the desired peptide or non-peptide. Solid substrates which present hydroxyl groups as the points of attachment for the first stage of the synthesis are commonly used, for example substrates which present hydroxyl groups as derivatives of benzyl alcohol, the peptide or non-peptide being attached as a benzyl ester and cleaved by hydrolysis, transesterification or aminolysis to release the peptide or non-peptide as a carboxylic acid, carboxylate ester or as a carboxamide. Also used are substrates which present amino groups, for example as derivatives of diphenyimethylamine, the peptide or non-peptide being attached as a carboxamide and cleaved by hydrolysis to release the peptide or non-peptide as a carboxamide. Substitution of such linkers by a nitro group can enable the photolytic cleavage of the peptides or non-peptides from the residue of the solid substrate.
Hydroxamic Acid Derivatives
Certain hydroxamic acid derivatives possess useful biological activities. Examples of such hydroxamic acids include compounds that inhibit urease (Odake S et al., Chem. Pharm. Bull., 1992, 40, 2764-2768), trypanosome glycerol-3-phosphate oxidase (Grady et al.. Mol Biochem. Parasitol, 1986, 19, 231-240), dehydropeptidase-1 (EP-B-276,947), ribonucleotide reductase (Farr R A et al., J. Med. Chem., 1989, 32, 1879-1885), 5-lipoxygenase (Kerdesky F A J et al., Tetrahedron Lett., 1985, 26, 2134-2146; U.S. Pat. No. 4,731,382), substance P degradation (Laufer R et al, Eur. J. Biochem., 1985, 150, 135-140), cardiovascular metalloproteinase enzymes (Turbanti L et al., J. Med. Chem., 1993, 36, 699-707; WO-9428012) and matrix metalloproteinase enzymes (Schwartz M A, Van Wart H E, Prog. Med. Chem., 1992, 29, 271-334).
Compounds which have the property of inhibiting the action of metalloproteinases involved in connective tissue breakdown such as collagenase, stromelysin and gelatinase (known as "matrix metalloproteinases", and herein referred to as MMPs) are thought to be potentially useful for the treatment or prophylaxis of conditions involving such tissue breakdown, for example rheumatoid arthritis, osteoarthritis, osteopenias such as osteoporosis, periodontitis, gingivitis, corneal, epiderrmal or gastric ulceration, and tumour metastasis, invasion and growth. It has been found that hydroxamic acid MMP inhibitors can also inhibit the production of the cytokine tumour necrosis factor (herein referred to as "TNF") (Mohler et al., Nature, 1994, 370, 218-220; Gearing A J H et al., Nature 1994, 370, 555-557; McGeehan G M et al., Nature 1994, 370, 558-561). Compounds which inhibit the production or action of TNF are thought to be potentially useful for the treatment or prophylaxis of many inflammatory, infectious, immunological or malignant diseases. These include, but are not restricted to, septic shock, haemodynamic shock and sepsis syndrome, post ischaemic reperfusion injury, malaria, Crohn's disease, mycobacterial infection, meningitis, psoriasis, congestive heart failure, fibrotic disease, cachexia, graft rejection, cancer, autoimmune disease, rheumatoid arthritis, multiple sclerosis, radiation damage, toxicity following administration of immunosuppressive monoclonal antibodies such as OKT3 or CAMPATH-1 and hyperoxic alveolar injury. Since excessive TNF production has been noted in several diseases or conditions also characterised by MMP-mediated tissue degradation, compounds which inhibit both MMPs and TNF production may have particular advantages in the treatment or prophylaxis of diseases or conditions in which both mechanisms are involved.
Classes of MMP Inhibitors
The known hydroxamic acid MMP inhibitors may be grouped into three classes; i) peptidyl hydroxamates, ii) succinyl hydroxamates and iii) arylsulfonamido hydroxamates.
i) The following patent publication discloses peptidyl hydroxamic acid-based MMP inhibitors: PA1 ii) The following patent publications disclose succinyl hydroxamic acid-based MMP inhibitors: PA1 iii) The following patent publication discloses arylsulfonamido hydroxamic acid-based MMP inhibitors: PA1 (i) forming a mixture of a liquid reaction medium and a solid phase reaction component which is substantially insoluble in the said liquid reaction medium and carries a plurality of covalently bound moieties of formula (A1) or (B1) ##STR12## in which formulae X represents the residual, non-hydroxamate, partial structure of the desired product, P.sub.1 represents hydrogen or an amino-protecting group, P.sub.2 represents hydrogen or a hydroxyl protecting group, and the bond designated (a) is one which covalently links the moieties (A1) or (B1) to the residue of the solid substrate and is cleavable under acid conditions or by photolysis; and PA1 (ii) in the resultant mixture, cleaving the said bond designated (a) and, if P.sub.1 or P.sub.2 as the case may be is not hydrogen, removing that protecting group P.sub.1 or P.sub.2 before, after or during cleavage of bond (a); and PA1 (iii) separating the resultant liquid reaction phase from the resultant reaction solids and recovering the desired product from the separated liquid reaction phase.
EP-A-345359 (Fuji)
The tri- and tetra-peptidyl hydroxamic acid derivatives disclosed in the above publication and described elsewhere (Odake S et al., Chem. Pharm. Bull., 1990, 38, 1007-1011; Odake S et al., Chem. Pharm. Bull., 1991, 39, 1489-1494; Odake S et al., Biochem. Biophys. Res. Commun., 1994,199, 1442-1446) can be regarded as having the following basic structure (I): EQU R.sub.1 --X.sub.1 --X.sub.2 --X.sub.3 --NHOH (I)
wherein the four groups R.sub.1, X.sub.1, X.sub.2 and X.sub.3 may vary according to the detailed disclosure of each of the publications.
U.S. Pat. No. 4,599,361 (Searle)
EP-A-0236872 (Roche)
EP-A-0274453 (Bellon)
WO 90/05716 (British Bio-technology)
WO 90/05719 (British Bio-technology)
WO 91/02716 (British Bio-technology)
EP-A-0489577 (Celltech)
EP-A-0489579 (Celitech)
EP-A-0497192 (Roche)
WO 92/13831 (British Bio-technology)
WO 92/22523 (Research Corporation Technologies)
WO 93/09090 (Yamanouchi)
WO 93/09097 (Sankyo)
WO 93/20047 (British Bio-technology)
WO 93/24449 (Celltech)
WO 93/24475 (Celltech)
U.S. Pat. No. 5,256,657 (Sterling Winthrop)
EP-A-0574758 (Roche)
WO 94/02446 (British Bio-technology)
WO 94/02447 (British Bio-technology)
WO 94/21612 (Otsuka)
WO 94/25434 (Celltech)
WO 94/25435 (Celltech)
The hydroxamic acid derivatives disclosed in the above publications can be regarded as having the following basic structure (II): ##STR2## wherein the five substituents R.sub.2 -R.sub.6 may vary according to the detailed disclosure of each publication. The balance of intrinsic level of activity, degree of specificity of inhibition of particular categories of MMP, physicochemical and pharmacokinetic properties can vary in an unpredictable way as the substituents R.sub.2 -R.sub.6 are varied.
EP-A-606046 (Ciba-Geigy)
The hydroxamic acid derivatives disclosed in the above publication can be regarded as having the following basic structure (III): ##STR3## wherein the four substituents R.sub.7 -R.sub.9 and Ar may vary according to the detailed disclosure of the publication.